Eton BoostSolar 5000 mAh Lithium Backup Battery Pack - Black (NBOSO5000B) Rechargeable lithium battery (5000mAh) enough to charge most smart phones two and one half times Rugged rubberized exterior, IPX-4 Splash proof 16 hours for full charge in sun - Micro USB to charge via Smartphone charger 7 hours for full charge 5V = 2.1A USB out to charge most smart phones and tablets Rechargeable/interchangeable 5000 mAH lithium battery pack